/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jackrabbit.webdav.lock;

import java.util.ArrayList;
import java.util.Iterator;

import org.apache.jackrabbit.webdav.property.AbstractDavProperty;
import org.apache.jackrabbit.webdav.property.DavPropertyName;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * The <code>SupportedLock</code> class encapsulates the lock capabilties of a
 * resource. It is mainly responsible for generating the &lt;supportedlock>
 * property.
 */
public class SupportedLock extends AbstractDavProperty {

	/**
	 * Class representing the default lock entries defined by <a
	 * href="http://www.ietf.org/rfc/rfc2518.txt">RFC 2518</a>.
	 */
	private final static class WriteLockEntry extends AbstractLockEntry {

		/** the lock scope */
		private final Scope scope;

		/**
		 * Creates a new WriteLockEntry
		 * 
		 * @param type
		 *            Can currently only be {@link Type#WRITE write}
		 * @param scope
		 *            Can currently only be {@link Scope#EXCLUSIVE exclusive} or
		 *            {@link Scope#SHARED shared}.
		 * 
		 * @throws IllegalArgumentException
		 *             If an argument contains invalid string
		 */
		WriteLockEntry(Type type, Scope scope) {
			if (!Type.WRITE.equals(type)) {
				throw new IllegalArgumentException("Invalid Type:" + type);
			}
			if (!Scope.EXCLUSIVE.equals(scope) && !Scope.SHARED.equals(scope)) {
				throw new IllegalArgumentException("Invalid scope:" + scope);
			}
			this.scope = scope;
		}

		/**
		 * @return returns {@link Scope#EXCLUSIVE} or {@link Scope#SHARED}.
		 * @see LockEntry#getScope()
		 */
		public Scope getScope() {
			return scope;
		}

		/**
		 * @return always returns {@link Type#WRITE write}.
		 * @see LockEntry#getType()
		 */
		public Type getType() {
			return Type.WRITE;
		}
	}

	/** the list of lock entries */
	private final ArrayList<LockEntry> entries = new ArrayList<LockEntry>();

	/**
	 * Creates a new empty SupportedLock property.
	 */
	public SupportedLock() {
		super(DavPropertyName.SUPPORTEDLOCK, false);
	}

	/**
	 * Adds a capability to this lock support.
	 * 
	 * @param entry
	 *            specifying the type of lock that is supported by this entry.
	 * @see LockEntry
	 */
	public void addEntry(LockEntry entry) {
		if (entry == null) {
			throw new IllegalArgumentException("The lock entry cannot be null.");
		}
		entries.add(entry);
	}

	/**
	 * Adds a capability to this lock support.
	 * 
	 * @param type
	 *            Can currently only be 'write'
	 * @param scope
	 *            Can currently only be 'exclusive' or 'shared'
	 * 
	 * @throws IllegalArgumentException
	 *             If an argument contains invalid string
	 */
	public void addEntry(Type type, Scope scope) {
		entries.add(new WriteLockEntry(type, scope));
	}

	/**
	 * Returns an iterator over all supported locks.
	 * 
	 * @return an iterator over all supported locks
	 */
	public Iterator<LockEntry> getSupportedLocks() {
		return entries.iterator();
	}

	/**
	 * Returns the list of supported lock entries.
	 * 
	 * @return list of supported lock.
	 * @see org.apache.jackrabbit.webdav.property.DavProperty#getValue()
	 */
	public Object getValue() {
		return entries;
	}

	/**
	 * Returns true if this a lock with the given type and scope is supported.
	 * 
	 * @param type
	 * @param scope
	 * @return true if applying a lock with the given type and scope is
	 *         basically supported.
	 */
	public boolean isSupportedLock(Type type, Scope scope) {
		Iterator<LockEntry> it = entries.iterator();
		while (it.hasNext()) {
			LockEntry le = it.next();
			if (le.getType().equals(type) && le.getScope().equals(scope)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Creates an XML element that represents the &lt;supportedlock> tag.
	 * 
	 * @return An XML element of this lock support.
	 * @param document
	 */
	@Override
	public Element toXml(Document document) {
		Element support = getName().toXml(document);
		Iterator<LockEntry> iter = entries.iterator();
		while (iter.hasNext()) {
			LockEntry le = iter.next();
			support.appendChild(le.toXml(document));
		}
		return support;
	}
}
